The invention relates to a screw-driving tool for implant screws having an elongate handle and having a bar-shaped tool which is anchored in the elongate handle.
Implant screws of a specific size may as a rule only be tightened with a limited torque for the connection of implant parts so that the thread or the pressed-together implant parts are not damaged. On the other hand, an implant screw must be tightened with a minimum torque so that it does not become loose. The manufacturer of implants which can be screwed in should therefore provide the possibility of carrying out such a screw connection while observing a predetermined torque. Tools for the screwing in of such screws should be capable of being easily sterilized and should show no wear due to their multiple use. A screw-driving tool which has a torque measurement and is licensed for non-sterile areas is shown in U.S. Pat. No. 5,048,381. U.S. Pat. No. 5,737,983 likewise shows general screw-driving tools with a torque bar which is limited against overload in its movement so that this limit can be felt in a tactile manner as a resistance in order to have reached a minimum torque with certainty. In contrast to the technical screw connections, in which a minimum tightening torque against the loosening of the screw connection is required, a certain tightening torque may not be exceeded with an implant screw. An overloading which is not controlled as it rises is therefore the same as a limit for the screwing in of an implant screw as the subjective feeling on the screwing in with a normal screwdriver. This is where the invention comes into play. Its object is to make the reaching of a permitted screwing torque known to the operating physician with certainty.